Begin by ensuring that both your ClickHouse and Oracle databases are properly set up and accessible. Confirm network connectivity between the systems and ensure that you have the necessary administrative privileges to both databases. Install the necessary client tools for each database system on your host machine, such as `clickhouse-client` for ClickHouse and `sqlplus` or `SQL Developer` for Oracle.

Use ClickHouse’s built-in tools to export the data you need. Execute a query to select the data and output it in a CSV format, which can be easily imported into Oracle. For example:
```bash
clickhouse-client --query="SELECT * FROM your_table" --format=CSV > data.csv
```
Ensure that the exported CSV file is stored in a location accessible for transfer to the Oracle environment.

Transfer the exported CSV file to the server or environment where your Oracle database is hosted. This can be done using secure copy protocols like SCP, SFTP, or any other secure file transfer method appropriate for your environment.

Log in to your Oracle database and create a table structure that matches the schema of your data being transferred. This involves defining the appropriate data types and constraints that correspond to your ClickHouse data. Use a script similar to the following, adjusting the table name and column definitions as necessary:
```sql
CREATE TABLE your_table (
column1 VARCHAR2(100),
column2 NUMBER,
...
);
```

Import the CSV data into a temporary staging table in Oracle using SQL*Loader or Oracle's external tables feature. For SQL*Loader, prepare a control file that specifies how to load the data, and run the loader:
```plaintext
LOAD DATA
INFILE 'path/to/data.csv'
INTO TABLE staging_table
FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"'
(column1, column2, ...)
```
Execute the following command:
```bash
sqlldr userid=username/password control=your_control_file.ctl
```

After loading the data into the staging table, run SQL queries to validate the integrity of the data. Check for missing, duplicate, or incorrect data entries and clean them as necessary. This step ensures that only accurate and clean data is moved to the final destination table.

Once the data is validated and clean, transfer it from the staging table to the final destination table using SQL operations. This can be done with an `INSERT INTO ... SELECT` operation:
```sql
INSERT INTO your_final_table (column1, column2, ...)
SELECT column1, column2, ...
FROM staging_table;
```
After transferring the data, you can remove the staging table if it is no longer needed.
By following these steps, you can manually transfer data from ClickHouse to an Oracle database without relying on third-party tools or connectors.